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Open Source Software: Antiques never die!



I just had this this request

> I'm looking for the sidereal variables used in Tom Clark's Basic Orbit
> program written several years ago.

This request refers to the original BASIC program I wrote more than 20 years
ago and published in AMSAT's ORBIT magazine (a predecessor of the Journal)
just before the launch pf Phase-3A (the satellite with the underwater
perigee). It was AMSAT's first attempt at "Open Source".

Back then we had 8080 CPUs running at a few MHz clock rates and a few were
rich enough to have  32 Kbytes (yes Kilo, not Mega) of RAM, and maybe a 180
kbyte floppy disk.

Since CPU cycles were very precious and RAM non-existent, my code used some
pre-computed "magic numbers". One of these was the Greenwich Mean Sidereal
Time at 00:00:00 on January Zeroth of the year. The yearly magic numbers had
to be entered every so often.

I had thought/wished that my antique software had died, but I guess that's
too much to ask for. So to answer the question once and for all, I hacked
some BASIC utilities I've used for years to make the table. If anyone really
needs it, the numbers thru Jan 0.0,2035 (more than 50 years after the
original publication) can now be found at

     http://www.toad.net/~w3iwi/sidtim.txt

In the continuing spirit of open-sourcedness, the source code that generated
this (for Microsoft's QB Quick Basic) can be found at

     http://www.toad.net/~w3iwi/sidtim.bas

This software contains a potentially useful resource in a series of
subroutines that convert between different date/time formats. It can
calculate the Modified Julian Date (MJD) or Day of Year, or Sidereal Time,
or GPS Week for any day between 1901 and 2099.

Now can we issue a "Do Not Resuscitate" order so that the 20 year old
software can die a natural death?

73 de Tom, W3IWI



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